从UWA打印多页

Question

I have about 8 records that I want to print in one batch, each on a separate page. However, the UWP sample for this uses over 600 lines of code to accomplish it. It seems to me that it has to be much, much easier than that. I thought all we'd have to do is add each page to the PrintDocument and send the print job. Apparently not. I'm using this:

async void Print()
{
    var printDocument = new PrintDocument();
    var printDocumentSource = printDocument.DocumentSource;
    var printMan = PrintManager.GetForCurrentView();
    printMan.PrintTaskRequested += PrintTaskRequested;

    var pages = new List<Page>();

    foreach (var item in items)
    {
        (//Set up variables)

        var printPage = new PageToPrint() { //Set properties };
        printPage.Set_Up();  //Set up fields

        pages.Add(printPage);
    }

    printDocument.SetPreviewPage(1, page);
    printDocument.SetPreviewPageCount(pages.Count, PreviewPageCountType.Final);

    foreach (var page in pages)
    {
        printDocument.AddPage(page);
    }

    printDocument.AddPagesComplete();
    await PrintManager.ShowPrintUIAsync();
}

void PrintTaskRequested(PrintManager sender, PrintTaskRequestedEventArgs e)
{
    PrintTask printTask = null;
    printTask = e.Request.CreatePrintTask("Kimble Print Job", sourceRequested =>
    {
        printTask.Completed += PrintTask_Completed;
        sourceRequested.SetSource(printDocumentSource);
    });
}

private async void PrintTask_Completed(PrintTask sender, PrintTaskCompletedEventArgs args)
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        PrintManager printMan = PrintManager.GetForCurrentView();
        printMan.PrintTaskRequested -= PrintTaskRequested;
    });
}

However, it won't generate the print preview. It just sits there spinning and spinning, and if I hit "print" it doesn't succeed (PDF can't open, job never gets to a physical printer.)

I was hoping printing would be at least reasonably easy with the PrintDocument , and I still think it looks like it should be. Am I just missing it here, or does it really take 600+ lines of code to dispatch a simple print job?

Answer 1

However, it won't generate the print preview.

This is because the setPreview method printDocument.SetPreviewPage(1, page); must be put in printDocument.GetPreviewPage event handle. So you should register the event handle firstly. Same with printDocument.AddPages event handle.You messed up the event handle register and callback function all in one.Here I do a little change of your code and I tested it works well.

protected PrintDocument printDocument;
protected IPrintDocumentSource printDocumentSource;
List<Page> pages = new List<Page>();
Page printPage = new PageToPrint();
public MainPage()
{
    this.InitializeComponent();
    RegisterForPrinting();
}

private async void BtnPrint_Click(object sender, RoutedEventArgs e)
{
    await PrintManager.ShowPrintUIAsync();       
}

public void RegisterForPrinting()
{
    printDocument = new PrintDocument();
    printDocumentSource = printDocument.DocumentSource;
    pages.Add(printPage);
    printDocument.GetPreviewPage += GetPrintPreviewPage;
    printDocument.AddPages += AddPrintPages;
    PrintManager printMan = PrintManager.GetForCurrentView();
    printMan.PrintTaskRequested += PrintTaskRequested;
}
private void AddPrintPages(object sender, AddPagesEventArgs e)
{
    foreach (var page in pages)
    {
        printDocument.AddPage(page);
    }
    printDocument.AddPagesComplete();
}
private void GetPrintPreviewPage(object sender, GetPreviewPageEventArgs e)
{
    printDocument.SetPreviewPage(1, printPage);
    printDocument.SetPreviewPageCount(pages.Count, PreviewPageCountType.Final);
}

void PrintTaskRequested(PrintManager sender, PrintTaskRequestedEventArgs e)
{
    PrintTask printTask = null;
    printTask = e.Request.CreatePrintTask("Kimble Print Job", sourceRequested =>
    {
        printTask.Completed += PrintTask_Completed;
        sourceRequested.SetSource(printDocumentSource);
    });
}

private async void PrintTask_Completed(PrintTask sender, PrintTaskCompletedEventArgs args)
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        PrintManager printMan = PrintManager.GetForCurrentView();
        printMan.PrintTaskRequested -= PrintTaskRequested;
    });
} 

Although you may not need all the code of the sample, but I recommend you to follow the official sample structure and build a PrintHelper class.